This type of device is known from DE 101 33 657 A1. The known device features a C-arm which can be rotated around the object, which features a radiation source at one end and a radiation detector at the other. To enable the radiation detector to be moved as close as possible to the object to be investigated, the radiation detector is supported so that it can rotated on the C-arm. As a result of the ability to rotate the radiation detector into any position relative to the C arm, the radiation detector can be aligned so that, despite that fact that it is as close as possible to the object to be examined, for example a patient, a patient table or such like, it does not collide with it. Thus the radiation detector of the known device does not have to be exchanged in particular applications. Instead it is possible to adapt the device to the relevant application by rotating the radiation detector.